Among location or position measurement systems using radio waves, Global Location or position System (hereinafter, referred to as GPS) is a widely used system. GPS is a system which measures location or positional relationship between GPS satellites and a receiver by utilizing GPS location or position signals transmitted from about 30 satellites traversing earth orbits and can be used to calculate the latitude, longitude, and altitude of a current site. Because the location or position signals from the satellites are used in GPS, there is a problem that the location or position in buildings or underground does not work.
Mobile phone tracking refers to the attaining of the current location or position of a mobile phone, stationary or moving. Localization may occur either via multilateration of radio signals between radio towers of the network and the phone, and/or via GPS. To locate the phone using multilateration of radio signals, it must emit at least the roaming signal to contact the next nearby antenna tower, but the process does not always require an active call. GSM is based on the signal strength to nearby antenna masts. Mobile location or position, which includes location or position based service that discloses the actual coordinates of a mobile phone bearer, is a technology used by telecommunication companies to approximate where a mobile phone, and thereby also its user (bearer), temporarily resides. The more properly applied term locating refers to the purpose rather than a location or position process. Such service is offered as an option of the class of location or position-based services (LBS).
The technology of locating is based on measuring power levels and antenna patterns and uses the concept that a mobile phone always communicates wirelessly with one of the closest base stations, so knowledge of the location or position of the base station implies the cell phone is nearby.
Advanced systems determine the sector in which the mobile phone resides and roughly estimate also the distance to the base station. Further approximation can be done by interpolating signals between adjacent antenna towers.
GSM localization is the use of multilateration to determine the location or position of GSM mobile phones, or dedicated trackers, usually with the intent to locate the user. Localization-Based Systems can be broadly divided into: Network-based; Handset-based; SIM-based; or Hybrid. Network-based techniques utilize the service provider's network infrastructure to identify the location or position of the handset. The advantage of network-based techniques (from mobile operator's point of view) is that they can be implemented non-intrusively, without affecting the handsets.
The accuracy of network-based techniques varies, with cell identification as the least accurate and triangulation as moderately accurate, and newer “Forward Link” timing methods as the most accurate. The accuracy of network-based techniques is both dependent on the concentration of base station cells, with urban environments achieving the highest possible accuracy, and the implementation of the most current timing methods.
Handset-based technology requires the installation of client software on the handset to determine its location or position. This technique determines the location or position of the handset by computing its location or position by cell identification, signal strengths of the home and neighboring cells, which is continuously sent to the carrier. In addition, if the handset is also equipped with GPS then significantly more precise location or position information is then sent from the handset to the carrier.
Cell phone and similar mobile devices have associated serial or identification numbers provided as codes. These codes include an Electronic Identification Number (“EIN”) (a unique 32-bit number programmed into the phone by the manufacturer), and a Mobile Identification Number (MIN), a 10-digit number derived from the phone's number.
The cell site relays these codes to the mobile telecommunications switching office in a process known as registration. The registration process is explained in the Department of Justice's
Electronic Surveillance Manual:
Cellular telephones that are powered on will automatically register or re-register with a cellular tower as the phone travels within the provider's service area. The registration process is the technical means by which the network identifies the subscriber, validates the account and determines where to route call traffic. This exchange occurs on a dedicated control channel that is clearly separate from that used for call content (e.g., audio)—which occurs on a separate dedicated channel. This registration process automatically occurs even while the cell phone is idle. Moving from one service area to another triggers the registration process anew. The cell site can even initiate registration on its own by sending a signal to the cell phone causing the phone to transmit and identify itself
It is possible to scan cell phones using suitable radio frequency scanners and computers to determine what the serial or identification numbers or codes are.
Current methods or systems for identifying potential suspects, conspirators, participants or witnesses for criminal activity suffer from problems such as lack of suitability for correct or practical identification, e.g., where security cameras record images of persons that cannot be properly identified due to clothing or attire that covers or blocks their faces or other distinguishing or identifying features or information.